▎ 摘　　要

In this study, we fabricated quantum point contacts narrower than 100nm by using an electrostatic potential to open the finite bandgap by applying a perpendicular electric field to bilayer graphene encapsulated between hexagonal boron nitride sheets. The conductance across the quantum point contact was quantized at a high perpendicular-displacement field as high as 1V/nm at low temperature, and the quantization unit was 2e(2)/h instead of mixed spin and valley degeneracy of 4e(2)/h. This lifted degeneracy state in the quantum point contact indicates the presence of valley polarized state coming from potential profile or effective displacement field in one-dimensional channel.